Where did these Spanish foods originate?

Spain, like many other countries, has a cuisine that has been influenced by other parts of the world. Many of the foods you mentioned are based on Mediterrean or Northern Africa cuisine. Lentils especially are an ancient food, mentioned in the Bible. The foods are also influenced by the travels of Spanish explorers as in the case of the chocolate. Chickens and other types of domesticated fowl have been around in most parts of the world for thousands of years. Sherry is a domestic wine of Spain, originating around the SW part of the country near the town of Jerez de la Frontera. Too sweet and cloying for me but good in certain cooking. Tomatoes originated in central and south America and were once thought to be poisonous and were only used for ornamentation or medicinal purposes. Chocolate also has its roots in the Amazon area. Chocolate mousse... awesome. Caramel is good in any form and is based on sugar. Sugar was first produced commercially in India but Spanish exploration in the Caribbean resulted in large sugar cane plantations. Spinach is of mid-Eastern culture and reflects the Moorish invasion and occupation of Spain. Spinach and pine nuts are excellent, different textures play off each other. Paella is actually the name of a large, flattish cooking pot that the peasants combined anything at hand to make cheap meals, usually rabbit, snails, whatever. We usually ociate it with the seafood mixtures of the Spanish coast which are the fisherman's version of stone soup. That is the typical restaurant fare if you order paella. All are good if cooked and seasoned properly. Pine nuts are the product of several species of pine trees and are grown in many parts of the world. Delicious in meat mixtures, on salads, or in cookies. Sangria is just the local red wine, mixed with the fruits of mostly citrus juices that are abundant in the Mediteranean area. Not to my taste, usually too sweet.